1. Field of the Invention
Film-forming inorganic compounds capable of being formed into flexible materials such as the compounds of the present invention have extensive industrial uses, for example, as coatings for paper, fiber, cloth, and the like. Further, these compounds may be used as flame and heat-resistant agents when incorporated into glass to raise the melting point thereof, and when used to impregnate wood products to raise the kindling point thereof; as rust inhibitive coatings; as refractory adhesives for ceramics; etc.
Moreover, the present invention relates to fireproof and fire-resistant composites, and to refractory flexible sheet composite covering materials for use in the interior of very tall buildings, and to heat-resistant, heat-insulative and sound-insulative materials for use in motor vehicles, ships, and the like. The invention also relates to a fire-resistant-covering process using these composite materials.
2. Description of the Prior Art
Sodium silicate has been used as an inorganic adhesive and coating material but has disadvantages, for example, it is hydroscopic, becomes carbonized easily and turns white, solidifies quickly and develops cracks, and tends to peel. Fluoride materials can be added to these coating materials to improve water-proofness, but this is not always sufficiently effective.
Silica sol and silica alkoxide are commercially available compounds. These compounds by themselves have no film-forming properties, but they may be modified by the addition of an organic compound to impart film-forming properties in materials. However, such modified materials fail to attain high temperature resistant and refractory properties. Teflon, a synthesis product of freon and an organic compound, has good heat resistance when compared with general synthetic resins, but is not qualified as a refractory.
There have been proposed, in U.S. Pat. Nos. 4,117,088, 4,029,747, 4,117,099 and Japanese Unexamined Patent Publication No. 51-132196, methods of preparing water-soluble inorganic complexes by the reaction of a metal with ammonia, or sulfuric or phosphoric acid or their salts, with an alkaline metal, but the products do not have any film-forming properties.
The so-called "hardening phenomenon" also occurs in the production of film-forming properties, and occurs due to the supersaturation of a solute in the formation of a film formed through gel bonding of the materials into a crystalline structure. Thus, in the above-mentioned U.S. patents, to a water-soluble inorganic complex was added materials such as silica sol, sodium silicate, pozzolan or fly ash to supersaturate a metallic component such as Si, which, however, results in the production of a film providing little film forming properties, that is, in its failure to form a flexible coating film. Aqueous solutions such as of sodium silicofluoride and sodium silicoborate can be dried to produce powders but fail to form coatings. Likewise glass, for example, as a compound of silicic acid, boric acid and an alkali metal hydroxide, may be adapted to prepare water soluble coatings.
As described above, Teflon, which is a fluorine-containing compound, cannot be processed into a high molecular coating film by the use of inorganic compounds, per se.
It therefore is an object of the present invention to provide a water-soluble film-forming inorganic compound having high molecular weight, without the need of a solvent, and which is capable of being formed into a flexible coating film.
For providing such film-forming properties as possessed by conventional organic coatings, it may be necessary to convert the inorganic compound into a high molecular weight compound. Fireproof and flame-proof characteristics are usually attributed to heat-resistant film-forming materials which are capable of blocking the supply of oxygen. Further, fireproof and flame-proof coating films suitable for metal plates and fibrous products are required to be flexible heat-resistant coating films. On the other hand, from the viewpoint of economy, it is best to avoid the use of a solvent, and polymerization associated with a high productivity is required.
The present invention has solved all of the above-mentioned problems.